The switched-capacitor amplifier is an electronic circuit element used for discrete-time signal processing. It works by moving charges into and out of capacitors when switches are opened and closed. Normally, the switched-capacitor amplifier is required to have fixed and accurate gain. However, one disadvantage for this circuit is that it burns a lot of power, mostly consumed by operational amplifier (opamp). The reason lies in that to achieve the target resolution, common practice is to employ very high-gain opamp (>80 dB) in addition to keep good matching between capacitors, so that the effects of limited gain and parasitic input capacitance of opamp can be ignored. The high-gain opamp usually needs three stages to implement. This makes opamp design complicated, requiring more branches to provide biasing current and extra common-mode feedback circuits to control the common-mode level at middle stages. All these factors contribute to the high power consumption. To make it worse, for stability issue, Miller-compensation is usually utilized and it also increases the probability of gain peaking and pole/zero interaction.
Therefore, an innovative design for switched-capacitor circuit is desirable.